For example, FIG. 7 is known as a conventional power switchgear equipped with a tank type vacuum circuit breaker. FIG. 7 is a longitudinal sectional view showing a conventional power switchgear disclosed in Patent Document 1.
In FIG. 7, an operating mechanism or a connection mechanism to an operating mechanism is provided on one end of a ground tank 2 through a support plate 3. An insulation support tube 5 is supported to the support plate 3 on one horizontal end in the ground tank 2, and a support insulator 6 is supported on the other horizontal end in the ground tank 2. A conductive movable side contact case 8 is supported to an insulation support tube 5 through an insulation support 7. A fixed side contact case 9 is supported to the support insulator 6. A movable side end portion and a fixed side end portion of the vacuum valve 10 serving as an interruption portion are horizontally supported to the movable side contact case 8 and to the fixed side contact case 9, respectively. The operating mechanism or the connection portion of the operating mechanism, which is located outside the ground tank 2, is connected to a movable contact 11 of the vacuum valve 10 through an insulation operating rod 12 which passes through in the insulation support tube 5 and the insulation support 7.
Then, the movable contact 11 of the vacuum valve 10 passes through the movable side contact case 8; and a movable side conductor 35 and a fixed side conductor 15 are electrically connected to the movable side contact case 8 and the fixed side contact case 9, respectively, and each conductor is provided in an inclined state to be extended upward. The movable side conductor 35 and the fixed side conductor 15 are surrounded by a bushing 16 and a bushing 17, respectively; and the upper end of the movable side conductor 35 is provided with a bushing terminal 20 and the upper end of the fixed side conductor 15 is provided with a bushing terminal 21. (See Patent Document 1 and FIG. 2.)
Furthermore, in a power switchgear equipped with other conventional tank type vacuum circuit breaker shown in FIG. 8, in addition to the configuration of the aforementioned conventional power switchgear, electric field relaxation shields 24 and 25 are arranged in a mode where the movable side contact case 8, the fixed side contact case 9, and end portions of the vacuum valve 10 are surrounded for the purpose of electric field relaxation of electric fields of the movable side contact case 8, the fixed side contact case 9, and the end portions of the vacuum valve 10. (See Patent Document 2 and FIG. 1.)    Patent Document 1: Japanese Unexamined Patent Publication No. 2007-306701    Patent Document 2: Japanese Unexamined Patent Publication No. 2003-319515